Halogenated organic compounds, such as polychlorinated biphenyls (PCBs), polybrominated and polychlorinated diphenyl ethers (PBDEs and PCDEs) are important Superfund and environmental contaminants. Complex mixtures of these compounds can be found in the environment. The research support described in this proposal is the following list includes all initially requested organohalogen compounds, which will be made available to the individual Research Projects: PCB congeners (Project #1, #2, #3, #4, #5 and #7), hydroxylated PCB metabolites (Projects #1, #2, #4 and #7), 3,4-Arene oxides (Project #1), benzoquinone metabolites and glutathione conjugates of PCBs (Project #1), PBDE and PCDE congers (Research Project #6). These compounds will be synthesized with straightforward synthetic approaches that are well established in our laboratory. Because of our extensive synthetic experience with the synthesis of organohalogen compounds, we are able to synthesize every compound of interest.